issue171:inkscape
Différences
Ci-dessous, les différences entre deux révisions de la page.
Les deux révisions précédentesRévision précédenteProchaine révision | Révision précédente | ||
issue171:inkscape [2021/08/03 19:07] – d52fr | issue171:inkscape [2021/08/06 09:54] (Version actuelle) – auntiee | ||
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Inkscape has long offered tracing of bitmaps using the Potrace library. While this does a fine job of vectorising raster graphics, it’s not the only open source tool that performs this trick. Autotrace is a command-line tool of similar vintage, which has now been integrated into the Trace Bitmap dialog. It’s available in the mode selection pop-up, in both single-scan and multiple-scan varieties. The latter is labelled as “Autotrace (slower)”, | Inkscape has long offered tracing of bitmaps using the Potrace library. While this does a fine job of vectorising raster graphics, it’s not the only open source tool that performs this trick. Autotrace is a command-line tool of similar vintage, which has now been integrated into the Trace Bitmap dialog. It’s available in the mode selection pop-up, in both single-scan and multiple-scan varieties. The latter is labelled as “Autotrace (slower)”, | ||
- | Ce mois-ci, je conclurai mon étude de la boîte de dialogue | + | Ce mois-ci, je conclurai mon étude de la boîte de dialogue |
Autotrace | Autotrace | ||
- | Inkscape propose depuis longtemps le traçage des bitmaps à l'aide de la bibliothèque Potrace. Bien que cette dernière fasse un excellent travail de vectorisation des graphiques | + | Inkscape propose depuis longtemps le traçage des bitmaps à l'aide de la bibliothèque Potrace. Bien que cette dernière fasse un excellent travail de vectorisation des dessins |
**Once selected, it offers two spinboxes and an “Invert image” checkbox. The latter, as the name suggests, inverts the image colors before tracing, making it easier to trace a light-on-dark design without having to manually process it first. The effect of the two spinboxes is somewhat harder to guess at. | **Once selected, it offers two spinboxes and an “Invert image” checkbox. The latter, as the name suggests, inverts the image colors before tracing, making it easier to trace a light-on-dark design without having to manually process it first. The effect of the two spinboxes is somewhat harder to guess at. | ||
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Une fois sélectionné, | Une fois sélectionné, | ||
- | La maigre documentation d' | + | La maigre documentation d' |
**Note that the higher iterations have reduced or wiped out the whites of the eyes, while the veins on the brain are a mere shadow of the original. The shape of the ear and of the brain’s outline are also significantly smoother. The total node count for the traced head is 485 for the top image and 410 for the bottom one. | **Note that the higher iterations have reduced or wiped out the whites of the eyes, while the veins on the brain are a mere shadow of the original. The shape of the ear and of the brain’s outline are also significantly smoother. The total node count for the traced head is 485 for the top image and 410 for the bottom one. | ||
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Notez que les itérations plus nombreuses ont réduit ou supprimé le blanc des yeux, tandis que les veines du cerveau ne sont qu'une ombre de l' | Notez que les itérations plus nombreuses ont réduit ou supprimé le blanc des yeux, tandis que les veines du cerveau ne sont qu'une ombre de l' | ||
- | La deuxième boîte à compteur, pour le réglage du « seuil d' | + | La deuxième boîte à compteur, pour le réglage du « Seuil d' |
**It’s pretty clear that the higher value results in a trace that is so smoothed out as to lose many of the original shapes completely. The top image, where the paths were much more heavily subdivided, consists of 587 nodes; the bottom one has only 327. | **It’s pretty clear that the higher value results in a trace that is so smoothed out as to lose many of the original shapes completely. The top image, where the paths were much more heavily subdivided, consists of 587 nodes; the bottom one has only 327. | ||
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Il est assez clair que la valeur la plus élevée donne un tracé tellement lissé qu'il perd complètement la plupart des formes originales. L' | Il est assez clair que la valeur la plus élevée donne un tracé tellement lissé qu'il perd complètement la plupart des formes originales. L' | ||
- | Comme je le conseille souvent dans cette rubrique, je suggère à la plupart des utilisateurs de commencer avec les valeurs par défaut pour les deux boîtes à compteur, et de ne commencer à les modifier que si vous avez besoin d' | + | Comme je le conseille souvent dans cette rubrique, je suggère à la plupart des utilisateurs de commencer avec les valeurs par défaut pour les deux boîtes à compteur, et de ne commencer à les modifier que si vous avez besoin d' |
- | La question la plus importante est peut-être de savoir comment les résultats d' | + | La question la plus importante est peut-être de savoir comment les résultats d' |
- | La première chose à noter est que la version d' | + | La première chose à noter est que la version d' |
**But it’s not that clearcut. The extremely thin lines on the brain are actually better preserved by the Autotrace algorithm. On the whole, I think the old Potrace code works best, at least in this case. But I also wouldn’t rule out creating a hybrid result by using node editing or Boolean operations to paste together the best parts from each result. | **But it’s not that clearcut. The extremely thin lines on the brain are actually better preserved by the Autotrace algorithm. On the whole, I think the old Potrace code works best, at least in this case. But I also wouldn’t rule out creating a hybrid result by using node editing or Boolean operations to paste together the best parts from each result. | ||
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Mais ce n'est pas aussi clair. Les lignes extrêmement fines sur le cerveau sont en fait mieux préservées par l' | Mais ce n'est pas aussi clair. Les lignes extrêmement fines sur le cerveau sont en fait mieux préservées par l' | ||
- | Autotrace (balayages | + | Autotrace (passes |
- | Qu'en est-il de l' | + | Qu'en est-il de l' |
**To you and I it may appear as though Autotrace spent several minutes producing a salmon-colored circle. But no: what you’re actually looking at is a group of 4180 objects! For comparison the Potrace version contains 8 objects – one for each color set via the “Scans” spinbox. | **To you and I it may appear as though Autotrace spent several minutes producing a salmon-colored circle. But no: what you’re actually looking at is a group of 4180 objects! For comparison the Potrace version contains 8 objects – one for each color set via the “Scans” spinbox. | ||
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And what of La Giaconda? After many minutes of processing my memory, swap and CPU were all maxed out, then Inkscape disappeared off my screen entirely. There was no appearance of the usual crash dialog I see when it dies, leading me to suspect that its demise was perhaps the fault of the Linux kernel killing it due to lack of available resources.** | And what of La Giaconda? After many minutes of processing my memory, swap and CPU were all maxed out, then Inkscape disappeared off my screen entirely. There was no appearance of the usual crash dialog I see when it dies, leading me to suspect that its demise was perhaps the fault of the Linux kernel killing it due to lack of available resources.** | ||
+ | À nous deux, il peut sembler qu' | ||
+ | Le fait de passer à la vue des contours suggère que les formes ont été tracées et qu' | ||
+ | |||
+ | Et qu'en est-il de La Joconde ? Après plusieurs minutes de traitement, ma mémoire, mon espace d' | ||
**Even with a “successful” trace, the sheer number of objects created is practically unmanageable. There may, perhaps, be some image types for which this mode offers an advantage, but I would try it only if the Potrace methods aren’t yielding acceptable results – and make sure to save your file first! | **Even with a “successful” trace, the sheer number of objects created is practically unmanageable. There may, perhaps, be some image types for which this mode offers an advantage, but I would try it only if the Potrace methods aren’t yielding acceptable results – and make sure to save your file first! | ||
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If Autotrace offers little or no improvement over Potrace, and in some cases is far too resource hungry, why bother adding it to Inkscape at all? The reason is that it offers one type of frequently requested tracing mode that Potrace does not – center line tracing. In fact the menu entries described previously are there only as a side-effect of including this mode. After all, if you’re adding the library anyway, why not also expose the standard tracing mode as well, to give your users more options.** | If Autotrace offers little or no improvement over Potrace, and in some cases is far too resource hungry, why bother adding it to Inkscape at all? The reason is that it offers one type of frequently requested tracing mode that Potrace does not – center line tracing. In fact the menu entries described previously are there only as a side-effect of including this mode. After all, if you’re adding the library anyway, why not also expose the standard tracing mode as well, to give your users more options.** | ||
+ | Même avec un tracé « réussi », le nombre d' | ||
+ | Traçage par Ligne centrale | ||
+ | |||
+ | Si Autotrace n' | ||
**Center line tracing is really applicable to only line art in which the shapes are made up of individual pen or pencil strokes. Using other tracing modes, each stroke is converted into a closed, filled path that reflects the thickness and shape of the original artwork. With this new mode, however, the tracing algorithm attempts to determine a single path that traces out a line following the middle of the original stroke. | **Center line tracing is really applicable to only line art in which the shapes are made up of individual pen or pencil strokes. Using other tracing modes, each stroke is converted into a closed, filled path that reflects the thickness and shape of the original artwork. With this new mode, however, the tracing algorithm attempts to determine a single path that traces out a line following the middle of the original stroke. | ||
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The real difference becomes clear when we take a closer look at the nodes used to make up the two traced paths. The first is a closed, filled path, so you can see that the nodes make up the outer shape of the stroke. The center line trace, on the other hand, results in an open path made up of a simple line of nodes: any suggestion of line thickness is purely down to the value set for the stroke width.** | The real difference becomes clear when we take a closer look at the nodes used to make up the two traced paths. The first is a closed, filled path, so you can see that the nodes make up the outer shape of the stroke. The center line trace, on the other hand, results in an open path made up of a simple line of nodes: any suggestion of line thickness is purely down to the value set for the stroke width.** | ||
+ | Le traçage de la ligne centrale ne s' | ||
+ | Pour l' | ||
+ | |||
+ | La véritable différence apparaît clairement lorsque l'on examine de plus près les nœuds utilisés pour constituer les deux tracés. Le premier est un tracé fermé, rempli, et vous pouvez voir que les nœuds constituent la forme extérieure du trait. Le tracé de la ligne centrale, en revanche, donne lieu à un tracé ouvert constitué d'une simple ligne de nœuds : toute l' | ||
**What happens when you try this mode with a more complex example? How about a few handwritten letters? | **What happens when you try this mode with a more complex example? How about a few handwritten letters? | ||
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You may also have realised that such shapes can’t be made up of a single path segment. In this instance we’ve ended up with a single complex path consisting of all the different segments that make up the letters combined into one object. Path > Break Apart allows us to reduce the complex path down to its constituent parts, which we can then give different colors to demonstrate the paths that the algorithm settled on.** | You may also have realised that such shapes can’t be made up of a single path segment. In this instance we’ve ended up with a single complex path consisting of all the different segments that make up the letters combined into one object. Path > Break Apart allows us to reduce the complex path down to its constituent parts, which we can then give different colors to demonstrate the paths that the algorithm settled on.** | ||
+ | Que se passe-t-il lorsque vous essayez ce mode avec un exemple plus complexe ? Que diriez-vous de quelques lettres manuscrites ? | ||
+ | Comme vous pouvez le constater, le tracé ne reflète pas vraiment les formes et le style d' | ||
+ | |||
+ | Vous avez peut-être aussi réalisé que de telles formes ne peuvent pas être composées d'un seul segment de trajectoire. Dans ce cas, nous nous sommes retrouvés avec un seul chemin complexe composé de tous les différents segments qui composent les lettres combinés en un seul objet. Chemin > Séparer nous permet de réduire le chemin complexe à ses parties constituantes, | ||
**The A, not unreasonably, | **The A, not unreasonably, | ||
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That’s not to say that the new mode is useless or unwelcome. For many images it will prove to be far more effective than the existing tracing methods, especially if you’re interested in only the core shapes of the elements rather than the exact details of the stroke outlines. Just remember that it’s working only with pixels, and has no concept of the order in which lines were laid down, or the difference between two lines that meet at an angle compared with a single line that has a sharp corner in it.** | That’s not to say that the new mode is useless or unwelcome. For many images it will prove to be far more effective than the existing tracing methods, especially if you’re interested in only the core shapes of the elements rather than the exact details of the stroke outlines. Just remember that it’s working only with pixels, and has no concept of the order in which lines were laid down, or the difference between two lines that meet at an angle compared with a single line that has a sharp corner in it.** | ||
+ | Le A, comme il se doit, est composé de trois trajectoires distinctes. Mais la complexité du B n'est saisie que par deux tracés : une ligne courbe complexe qui englobe la majeure partie de la forme de la lettre, et un petit segment droit pour combler l' | ||
+ | Vous pouvez penser que je suis injuste avec l' | ||
+ | |||
+ | Cela ne veut pas dire que ce nouveau mode est inutile ou malvenu. Pour de nombreuses images, il s' | ||
**As is so often the case with the Trace Bitmap dialog, I can only recommend that you give it a try on your image, but don’t expect miracles. Even if the results aren’t perfect, it may save you some manual tracing time on part of your design, or at least give you a starting framework to build upon. | **As is so often the case with the Trace Bitmap dialog, I can only recommend that you give it a try on your image, but don’t expect miracles. Even if the results aren’t perfect, it may save you some manual tracing time on part of your design, or at least give you a starting framework to build upon. | ||
Next month, we’ll take a look at the new “Selectors and CSS” dialog, which promises to make Inkscape a little more useful as a web development tool.** | Next month, we’ll take a look at the new “Selectors and CSS” dialog, which promises to make Inkscape a little more useful as a web development tool.** | ||
+ | |||
+ | Comme c'est souvent le cas avec la boîte de dialogue Vectoriser un objet matriciel, je ne peux que vous recommander de l' | ||
+ | |||
+ | Le mois prochain, nous nous pencherons sur la nouvelle boîte de dialogue « Sélecteurs et CSS », qui promet de rendre Inkscape un peu plus utile en tant qu' | ||
issue171/inkscape.1628010474.txt.gz · Dernière modification : 2021/08/03 19:07 de d52fr